Controlling system for sewing machines



United States Patent [72] Inventors Hubert ,Iuenemann and Hans Scholl,

Bielel'eld, and Wilfried Strothmann, Anshausen B. lielefeldG'er'lnany 767,598

.(.l l2/Air Digest) .(.1 12/Air Digest) ll2/Air Digest 1 12/130 2,539,131 1/1951 Gundersen et 3,204,591 9/1965 Pickett 3,252,437 5/1966 Pickett.........

211 AppLNo. 22] Filed Aug.28, 1968 45 Patented Dec. 22, 1970 Assignee werke Miller et al.

Blelefeld, Germany Primary Examiner-Alfred R. Guest [32] Priority Sept. 6, 1967 Attorney-Jacob L. Kollin [33] Germany [31 1 No. X63392 ABSTRACT: A controlling system for sewing machines or automatic sewing devices with an actuating device for control switch means operated by passing a workpiece through a medium which cannot penetrate a workpiece. The actuating device, arranged in the path of motion of the workpieces, con- 112/252 sists of an air barrier comprising an air draft penetrating the D055 65/00 passageway of the workpieces and a reflecting plate arranged in the effective range of the air draft and forming a part of the operating means for the control switch means.

(Au ean ratio), 130, 129

Ill= CONTROLLING SYSTEM FOR SEWING MACHINES BACKGROUND OF THE INVENTION The present invention relates to a device adapted for use in sewing machines or automatic sewing devices an serves to actuate control switch means by passing of a workpiece through a medium which cannot penetrate it.

Such contactless controlling means using so-called light barriers in the form of a light source and 'a light sensitive tube are generally known in industry and are also used for controlling sewing machines.

A valve system for controlling a pressure fluid to a thread cutter combined with a sewing machine has been developed, which comprises a photoelectric light barrier'for controlling the cutting means for cutting off the thread chain formed between successive workpieces and which employs a medium which cannot penetrate a workpiece.

Such a system is disclosed, for example, in Myska US. Pat. No. 3,250,237 granted May 10, 1966 and German DUR- KOIPWERKE utility-model Pat. No. 1,893,796 published May 27, 1964.

Such light barriers, to the extent that they are employed for controlling sewing machine devices, are unprofitable, since they are relatively expensive. The electric power delivered from electric light elements is not capable of exciting an electromagnet or an electromagnetic valve without the use of an additional amplifier. Only in rare cases is it possible for a mechanic employed by the sewing workshop to repair the light barrier in case of its failure.

It is the general object of this inventionto provide a new and improved system for the touchless controlling of the actuation of control switches or valves at the beginning and/or the end of the passage of a workpiece through a sewing machine for automatic operations, e.g. the cutting of threads.

It is a further object of the invention to provide a controlling system for sewing machines which is safe in operation, inexpensive to manufacture and simple in construction.

A further object of the invention is to provide controlling systems for sewing machines which require fewer component parts than conventional contactless controlling systems.

Another object of the invention is to provide a contactless controlling device for sewing machines which can be installed with relative ease in existing machines.

SUMMARY In accordance with the main feature of the invention, there is provided in a sewing machine having stitch'forming means and workpiece feeding means, an actuating 'device for control switch means operated by passing of a workpiece through a medium which cannot penetrate said workpiece. This actuating device is arranged in the path of motion of the workpieces and consists of an air barrier comprising an air draft which penetrates the passageway of the workpieces, and a reflecting plate arranged in the effective range of the air draft and forming a part of the operating means for the control switch means.

According to another feature of the invention, the barrier comprises an air nozzle which is arranged in the slide plate of the sewing machine, an air draft conduit pipe above the air nozzle and within the effective range of the air draft leaving the air nozzle and a gap therebetween, and a' reflecting plate above the air draft conduit pipe and within the effective range of the air draft leaving it, while the reflecting plate forms a part of the operating means for the control switch means. The reflecting plate may be provided with a cup-shaped part.

According to a further feature of the invention, the air nozzle arranged in the slide plate consists of an angular hose liner flattened and soldered into a cutout of the slide plate. This hose liner is closed at its one end and provided with an air outlet. The air nozzle may be slidably arranged in the throat plate and may consist of a nipple provided with an air outlet.

Other and more specific objects and features of the invenpreferred embodiments, when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of part of a sewing machine with a thread cutter and the controlling system of the invention;

FIG. 2 is a side elevational view of part of a sewing machine using a second modification of the invention;

FIG. 3 is a vertical section on substantially the line III-III of FIG. 1, on an enlarged scale;

FIG. 4 is a horizontal section on the hire IV-IV of FIG. 3;

FIG. 5 is a side elevation of a part of the lower part of the air draft conduit pipe provided with a workpiece deflector, on an enlarged scale;

FIG. 6 is an air draft conduit pipe with an air inlet opening staggered opposite to the air exit opening, on en enlarged scale;

FIG. 7 shows a further modification of an air barrier, in section; and

FIG. 8 is a top plan view along the line VIII-VIII of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of the drawings, the sewing machine has the usual bedplate I, a standard 2 and an arm (not shown) which terminates in the head 3. Supported in the head 3 are a needle bar 4 and a presser bar 5 with a presser foot 6, whose sole 7 cooperates with a throat plate 8.

In a slide plate 9 there is provided an air nozzle 10, formed by an angular hose liner 11 which is flattened and closed at its one end and soldered in a cutout 12 in the slide plate 9 (FIGS. 3 and 4). The angular hose liner 11 is further provided with an air outlet 13 directed vertically upward. On the free end of the hose liner ll, directed diagonally downward, there is secured a hose 14 which extends to a pressure air source (not shown) and which is under pressure of about 1.2 to 1.5 atmospheric excess pressure.

The air draft leaving the air outlet 13 has a diameter of 0.2 to 0.5 mm. and is caught by an air inlet opening 15 of an air draft conduit pipe 16 which is arranged at a sufficient distance above the air outlet 13 to allow the passage of a workpiece 17 (FIG. 3). The air draft conduit pipe 16 is inserted in a sheet iron angle 18, which is secured to the head 3 of the sewing machine by screws 19 (FIG. 1

Attached to the angle sheet iron 18 is an electric microswitch 20, the switch arm 21 of which is made of wire and provided at its free end with a reflecting plate 22, appropriately provided with a cup-shaped part 22', disposed on the air exit opening 23 (FIG. 3) when there is no airflow, i.e. when the workpiece 17 interrupts said airflow.

The microswitch 20 controls a magnetic valve (not shown) by means of a short time relay, for the emission of an air im pulse to an air cylinder 24, the piston 25 of which temporarily operates, through a connecting rod 26 and a knifeholder 27, the knife 28 for cutting the thread chain between two workpieces. The release is effected by means of a pressure spring 29. The air cylinder 24 and the connecting rod 26 with the knifeholder 27 are accommodated in a supporting member 30 which is slidable in oblong holes 31 and is clamped to the head 3 by means of screws 19.

tion will be apparent from the following description of The device operates as follows:

When the workpiece 17 (FIG. 3) is disposed between the air outlet 13 and the air draft conduit pipe 16, the air draft will be interrupted and the reflecting plate 22 of the microswitch 20 will lie on the air exit opening 23 of the air draft conduit pipe 16. When the workpiece 17 releases the air draft, the reflecting plate 22 is lifted by the air draft and the microswitch 20 controls the knife 28 in a manner already described. The workpiece deflector 32 prevents the possible rising of the workpiece 17 along the air draft conduit pipe I6 after sewing has started.

From the time the microswitch 2% has made contact until the response of the knife 28, owing to the time delays required for the production of a magnetic field, a certain time passes. During this time, the end of the workpiece 17, after leaving the sole 7 of the presser foot 6 has to be led backward out of the effective range of the knife 28 so that it will not impinge upon the workpiece 17 but upon the thread chain.

The thread chain length remaining beyond the workpiece, after the thread chain has been chopped off, depends on the passage speed of the workpiece through the sewing machine and on the distance between the air barrier and the knife 28. At a constant passage speed of the workpiece through the sewing machine, the required thread chain length remaining beyond the workpiece, can easily be regulated by displacing the supporting member 30 relative to the air draft conduit pipe 16.

The same can also be achieved with a stationary mounted knife 2&3, as shown in FIG. 2, and a tripartite air draft conduit pipe 33, the hose liner 3 3 of which is embraced by a pipe sadtile 35, which is slidably secured to the presser bar by means of an oblong hole 36', and the upper hose liner 37 of the air draft conduit pipe 33, forming the air exit opening 23 and being connected by means of a flexible hose 36, fixedly arranged at the head 3 together with the microswitch 20 by means of a support 38.

As can be seen in FIG. 2, it is possible to deflect the air draft after its entry into the air inlet opening into any direction in order to arrange the microswitch at the most suitable place.

As shown in FIG. 6, the air draft conduit pipe 39, provided with an air inlet opening 23, can also consist of an adequately bent pipe.

A further form of construction of an air barrier is shown in FIGS. 7 and 8. Here, an oblong hole 40 is provided in the throat plate 8, a nipple 41 being displaceably arranged in feed direction and clampable by means of a nut 42. The air draft reaches the reflecting plate 22, through an air exit hole 43 when no workpiece is disposed above the air exit hole 43.

As shown in FIG. 5, the workpiece deflector 44 can also consist of an upwardly arched plate 45.

The advantage of the devices for the contactless automatic control of control means when passing a workpiece through a sewing machine, compared with other devices known until now, can be seen in the fact, that these devices are extraordinarily simple and inexpensive, reliable in performance and require no maintenance.

Although the invention has been described in its preferred forms, it is understood that the present disclosure of the preferred forms has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of part may be resorted to without departing from the spirit and the scope of the invention.

We claim:

1. In a sewing machine having a throat plate, a slide plate, stitch forming means and workpiece-feeding means and control switch means for controlling of operating means of said sewing machine, an actuating device for operating said control switch means by passing of a workpiece through a medium which cannot penetrate said workpiece, said actuating device arranged in the path of motion of said workpiece consisting of an air barrier, said air barrier comprising an a r nozzle arranged in said slide plate of said sewing machine, an air draft conduit pipe above said air nozzle and within the effective range of the air draft leaving said air nozzle and with a gap between said nozzle and said pipe, and a reflecting plate above the discharge end of said air draft conduit pipe and within the effective range of said air draft leaving it, said reflecting plate forming a part of the operating means for said control switch means.

2 In a sewing machine as defined in claim ll, wherein said reflecting plate is provided with a cup-shaped part.

3. In a sewing machine as defined in claim ll, wherein said slide plate is provided with a cutout, and said air nozzle arranged in said slide plate consists of an angular hose liner flattened and soldered into said cutout, said hose liner closed at its one end and provided with an air exit hole.

4. In a sewing machine as defined in claim 1, wherein said air nozzle arranged in said throat plate consists of a nipple provided with an air exit hole, said nipple mounted slidable and determinable in said throat plate.

5. In a sewing machine as defined in claim 1, wherein said air barrier consists of a nipple provided with an air exit hole and mounted slidable and determinable in said throat plate, and a reflecting plate arranged in the effective range of said air draft leaving said air exit hole and forming a part of the operating means for said control switch means.

6. In a sewing machine defined in claim 1, wherein said air draft conduit pipe is provided with an air inlet opening staggered opposite to the air exit opening.

7. In a sewing machine as defined in claim 1, wherein said air draft conduit pipe consists of a flexible hose.

8. In a sewing machine defined in claim I, wherein said air draft conduit pipe is provided at its lower end with a workpiece deflector consisting of an upwardly arched plate.

9. In a sewing machine having stitch-forming means, workpiece-feeding means, a throat plate, a slide plate and cutter means adjacent said stitch-forming means for severing the thread chain between two workpieces, an actuating device for said cutter means, control switch means for operating said actuating device, actuated by passing of said workpieces through a medium, which cannot penetrate said workpiece, said actuating device arranged in the path of motion of said workpieces and consisting of an air barrier comprising air draft means for penetrating the passageway of said workpieces and a reflecting plate arranged in the effective range of said air draft means and forming a part of the operating means for said control switch means controlling said cutter means.

10. In a sewing machine as defined in claim 9, wherein said air barrier means comprises an air nozzle arranged in said slide plate and an air draft conduit pipe above said air nozzle and within the effective range of the air draft leaving said air nozzle and having a gap between said nozzle and said pipes said reflecting plate arranged above the discharge end of said air draft conduit pipe and within the effective range of said air draft leaving said pipe.

11. In a sewing machine as defined in claim 10, wherein said air nozzle arranged in said slide plate consists of an angular hose liner flattened and soldered into a cutout of said slide plate, said hose liner being closed at its one end and provided with an air exit hole, and said air draft conduit pipe provided at its lower end with a workpiece deflector formed as a presser foot sole.

12. In a sewing machine as defined in claim 10, further provided with a presser bar carrying a presser foot, and wherein said air draft conduit pipe consists of a hose liner provided at its lower end with workpiece deflector means slidably secured to said presser bar, an upper hose liner for cooperation with said reflecting plate and a flexible hose between said hose liners, and wherein said air nozzle arranged in said throat plate consists of a nipple provided with an air exit hole, said nipple mounted slidable and determinable in said throat plate.

I 13:. In a sewing machine having a bedplate, a standard, a head, stitch-forming means, workpiece-feeding means, a throat plate, a slide plate, a presser bar carrying a workpiece presser means; cutter means adjacent said stitch-forming means for severing the thread chain between two workpieces, an actuating device for said cutter means, control switch means for operating said actuating device by passing of said workpiece through a medium which cannot penetrate said workpiece, said actuating device arranged in the path of motion of said workpiece and consisting of an air barrier means including an air nozzle arranged in said slide plate, comprising an angular hose liner closed at its one end and provided with 1,,

an air exit hole, flattened and soldered into a cutout of said slide plate, and further including an air draft conduit pipe having a workpiece deflector formed as a presser foot sole and arranged above said air nozzle within the effective range of the air draft leaving said air exit hole and with a gap between said deflector and said slide plate, and a reflecting plate forming a part of the operating means for said control switch means and arranged above the discharge end of said air draft conduit pipe within the efiective range of said air draft leaving the pipe, said cutter means comprising a knife for cooperating with said throat plate, a knife holder carrying saidknife; a connecting rod carrying said knife holder, a supporting member slidably secured to said sewing machine head for slidably receiving said connecting rod, a driving means mounted on said supporting member, and a spring for holding said knife in an upper position when said driving means is inoperative.

14. In a sewing machine as defined in claim 13, wherein said air barrier comprises a hose liner provided at its lower end with said workpiece deflector and slidably secured to said presser bar in feed direction of said workpieces, an upper hose liner for cooperation with said reflecting plate, a flexible hose between said hose liners, and a nipple provided with an air exit hole and mounted slidably in the workpiece feed direction and determinable in said throat plate. 

